1. Field of the Invention.
The present invention relates to a guidewire having a controlled radiopacity tip. More specifically the present invention relates to a guidewire having a central core wire with a tapered end fixed at its distal end to a rounded tip and a coiled spring wire having its outer distal end also connected to the rounded tip. The coiled spring wire is a non-radiopaque coiled wire and a second radiopaque coiled spring wire is fixed at a proximal end to the center core wire near the beginning of the taper thereof and at a distal end to the rounded tip. The radiopaque coil is interwound or interleaved with the outer non-radiopaque coil and also fixed to the rounded tip. Preferably the spacing between the interleaved radiopaque coils and non-radiopaque coils increases from the beginning of the interleaving to the rounded tip.
2. Description of the related art including information disclosed under 37 CFR .sctn..sctn.1.97-1.99.
Heretofore, coiled spring guidewires have been proposed having varying radiopacity and having varying spacing or varying pitch in the coils at the distal end thereof to provide more flexibility in the distal end portion of the guidewire. Examples of some of these previously proposed guidewires are disclosed in the following U.S. Pat. Nos.:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 4,721,117 Mar et al. 4,748,986 Morrison et al. 4,763,647 Gambale 4,813,434 Buchbinder et al. 4,846,186 Box et al. 4,922,924 Gambale et al. 5,063,935 Gambale 5,144,959 Gambale et al. 5,147,317 Shank et al. 5,174,302 Palmer 5,178,158 de Toledo 5,253,653 Daigle et al. 5,259,393 Corso, Jr. et al. ______________________________________
The Mar et al. U.S. Pat. No. 4,721,117 discloses a guidewire with flexibility and ease of shaping.
The Morrison et al. U.S. Pat. No. 4,748,986 discloses a coiled spring floppy guide wire with opaque tip. The coils in the distal end portion of the guidewire are highly opaque and stretched or spaced to provide flexibility.
The Gambale U.S. Pat. No. 4,763,647 discloses a steerable guidewire which provides for a change in the radiopacity of the distal portion of the guidewire to provide a more radiopaque segment at the distal portion than at more proximal portions. Gradual selected transitions of stiffness of the guidewire are achieved by varying the spacing of the individual turns of an outer coil and an inner coil surrounding a core wire at the distal end portion of the guidewire.
The Buchbinder et al. U.S. Pat. No. 4,813,434 teaches a steerable guidewire with a deflectable tip that is made deflectable by providing stretched coils in the distal end portion of the guidewire.
The Box et al. U.S. Pat. No. 4,846,186 discloses a coiled spring guidewire. The coils of a coiled spring wire of the guidewire are less tightly packed in the distal end portion of the guidewire to define gaps or spaces.
The Gambale et al. U.S. Pat. No. 4,922,924 teaches a guidewire having segments of varying radiopacity. For this purpose the guidewire includes a coil at the distal end which is formed from a highly radiopaque coil and a non-radiopaque coil arranged in bifilar arrangement to define a moderate radiopacity section in which the radiopaque and non-radiopaque segments alternate.
The Gambale U.S. Pat. No. 5,063,935 discloses a guidewire with varying radiopacity. The guidewire includes an outer small diameter highly radiopaque coiled wire. An inner helical coil formed from a larger diameter highly radiopaque wire is disposed within the outer coil and is attached at its proximal end to the distal end of a core wire shaft and at its distal end to a rounded tip within the outer coil. This guidewire defines an arrangement which, when viewed fluoroscopically, has a highly radiopaque distal portion and a moderately radiopaque proximal portion.
The Gambale et al. U.S. Pat. No. 5,144,959 teaches a catheter guidewire with varying radiopacity similar to the guidewire disclosed in U.S. Pat. No. 5,063,935 with the exception that the distal end portion has regions of high radiopacity, moderate radiopacity and relatively no radiopacity.
The Shank et al. U.S. Pat. No. 5,147,317 teaches a varied radiopacity guidewire which has a distal tip which presents a relatively dark radiopaque image and proximal portions which present a less radiopaque, relatively gray, image.
The Palmer U.S. Pat. No. 5,174,302 teaches a guidewire with varied radiopacity and spaced, highly radiopaque regions which are established by banded portions that are highly radiopaque.
The de Toledo U.S. Pat. No. 5,178,158 teaches a convertible guidewire-catheter with a soft tip having spaced apart flat wire coils in a distal end thereof to render the distal end more flexible.
The Daigle et al. U.S. Pat. No. 5,253,653 discloses a fluoroscopically viewable guidewire for a catheter. The guidewire has a core wire disposed within a coiled spring wire and a linear array of radiopaque markers disposed on the core wire adjacent the distal tip of the guidewire.
The Corso, Jr. et al. U.S. Pat. No. 5,259,393 discloses a guidewire having a controlled radiopacity tip. The guidewire includes an outer loosely coiled proximal region which is less radiopaque and a tightly coiled distal region which is more radiopaque.
Also, a guidewire having spaced apart radiopaque marker bands on a core wire surrounded by a plastic sleeve is disclosed in U.S. application Ser. No. 07/942,777.